<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .circle {
            width: 100px;
            height: 100px;
            border-radius: 50%;
            margin: 0 auto;
            --d: 60deg;
            /* 锥形渐变 */
            background: conic-gradient(#f00 var(--d),
                    #0f0 var(--d) 120deg,
                    #00f 120deg 240deg,
                    #c213c2 240deg 360deg);
            position: relative;
        }

        .circle::before {
            content: '';
            position: absolute;
            background: #fff;
            inset: 5px;
            border-radius: 50%;
        }
    </style>
</head>

<body>
    <div class="circle"></div>
</body>

</html>